Ocular procedures often modify one or more structures of the eye, such as the cornea, lens, or retina. Some procedures involve removing or replacing one or more structures of the eye, or adding an implant. For example, lens replacement surgery involves removing a patient's existing lens and replacing it with a new lens. Some procedures, such as laser vision correction surgery, do not remove or replace existing structures of patient's eye, or add an implant to the eye, but rather re-shape existing structures. Regardless of the type of modification being made (e.g., removal, replacement, insertion, or alteration), the optical performance of the eye is altered by the alteration of the structures of the eye.